Evaluating the effect of different processing methods on fermented soybean whey-based tofu quality, nutrition, and flavour

The diverse and complex processing technologies used to produce tofu leads to the production of tofu with varying yield, quality, and flavour characteristics. In this study, tofu was produced using the gel-forming principle of soybean protein coagulation of fermented soybean whey (FSW), the filtering-to-boiling method (FBM), boiling-to-filtering method (BFM), and repeated boiling-to-filtering method (RBFM). An evaluation of sensory attributes, physicochemical properties, textural characteristics, microstructure, isoflavones, and flavour components of tofu was conducted. The RBFM group exhibited the highest yield (255.34%), water holding capacity (73.42%), and protein content (19.12%). The BFM and RBFM tofu outperformed the FBM tofu in terms of textural characteristics, microstructure, and sensory traits. The tofu yield positively correlated with protein content, WHC, and hardness (r = 0.902, 0.879, and 0.878, respectively). Compared to FBM, the content of aglycone isoflavones (daidzein, glycitin, genistein) and beany flavour components (1-hexanol, (E)-2-hexenol) in BFM and RBFM tofu were significantly higher (P < 0.05), while β-glucosides isoflavones (daidzin, glycitin, genistein) and n-hexanal were significantly lower (P < 0.05),. Overall, tofu made by the RBFM method yielded the highest quality products. The goal of this study was to provide a theoretical basis and offer technical support for the production of commercial-grade tofu.